1. Field of the Invention
The present invention relates to a method of manufacturing a semiconductor device, and more particularly, to a method of forming a titanium nitride film and a method of manufacturing a semiconductor device using the same.
2. Description of the Related Art
An adhesive layer having a Ti/TiN structure is generally employed in order to improve the poor adhesive characteristic of a metal such as tungsten (W) for filling a contact hole, when a metal contact plug required for the metal wiring of a semiconductor device is formed.
In a conventional technology, a physical vapor deposition (PVD) method such as a sputtering method is used for forming the adhesive layer having the Ti/TiN structure. However, when the Ti/TiN structure is formed by the PVD method, a film having a poor step coverage is obtained. Therefore, in the case of forming a contact having a large aspect ratio, the overhang of the Ti/TiN film is severe at the entrance of the contact hole when the Ti/TiN film is used as the adhesive layer or a barrier layer. Accordingly, a large void is formed in the contact during a subsequent process of depositing a tungsten film. Also, when the Ti/TiN film is too thin on the bottom of the contact due to the poor step coverage of the Ti/TiN film, WF.sub.6, gas, used as a source gas during a subsequent process of depositing the tungsten film, and Ti of the Ti/TiN film react, thus forming a nonconductor or vaporizing some part. Accordingly, the TiN film is lifted and peeled off. If so, the Ti/TiN film cannot serve as a barrier with respect to the WF.sub.6 gas.
Therefore, a process of forming a TiN film by a chemical vapor deposition
In particular, the TiN film formed by the CVD method using TiCl.sub.4 gas as a source gas is generally used as an adhesive layer of a metal film or a barrier film when a metal contact or a capacitor is formed since it is possible to obtain a good step coverage.
A large amount of chlorine (Cl) is included in the formed TiN film in the method of forming the TiN film by the CVD method using the TiCl.sub.4 gas as the source gas. The TiN film containing a large amount of Cl shows a high resistivity. Also, since Cl permeates and damages the Ti film which is an underlayer, a high temperature rapid thermal nitration (RTN) process, or an NH.sub.3 plasma process is required on the Ti film in order to prevent the Cl permeation.
When the high temperature RTN process or the NH.sub.3 plasma process is performed with respect to the Ti film, the following problems occur. Firstly, the number of processes increases and a semiconductor manufacturing process becomes complicated since the above process is added. Secondly, additional equipment should be introduced since the above process is added. As a result, the burden of equipment investment increases. Thirdly, shallow junctions have recently started to be realized in semiconductor devices. Therefore, the allowed thickness of the Ti film deposited as the barrier film in the contact hole is restricted. However, a considerable amount of Ti is consumed in the Ti film by the high temperature RTN process or the NH.sub.3 plasma process. As a result, it is not possible to secure a stable contact resistance since the amount of residing Ti becomes small.